This section explains the operation with a separate receiving antenna such as the Wellbrook loop, for example:
Transmit - doublet or dipole (ANT1),
Receive - loop antenna (RX).
With some of the more basic ANAN models such as the 10E the RX port (usually a SMA connector) is always inline during receive, so you will normally switch the transmitting antenna out of line during receive so only the loop antenna is active.
When you select the Antenna option RX/Ant 1 (ribbon bar, Home pane, Radio panel) the antenna selection is actually switched from Ant 1 to Ant 3 during receive so only the RX antenna is active. When you switch to transmit the antenna is switched back to Ant 1.